Flat abs are made in the gym—AND the kitchen. Use our 30 day ab challenge and eating strategies to get a flatter stomach in 30 days!

Day 1. Training Tip: Put Your Core First
If flat abs are important to you, promote them to the top of your fitness to-do list. "A lot of people exercise their abdominal muscles at the end of their workout, and that's when you get sloppy or run out of time," says Women’s Health Exercise Science Expert Rachel Cosgrove, C.S.C.S. "You should do them first, and then move on to your cardio. To get them looking great, you need to make them a priority." You'll be glad you did.

Day 2. Core-Sculpting Workout: Attack Your Hidden Core Muscles
Even women who are otherwise slender and fit can end up with a belly pooch due to underworked lower abdominal muscles. We created a workout to tap into the deep abdominal muscles—the transverse abdominis—that pull in your waistline like a corset. Get the 15-minute abs workout!

Day 3. Plank Test #1
This is the first of five plank tests. Hold a plank for as long as you can with proper form. Your goal is to build up to 90 seconds. How long can you hold it? Write down your time so you can track your progress. If you can already hold a plank for 90 seconds, try these plank upgrades.

How to do a plank: Starting at the top of a pushup position, bend your elbows and lower yourself down until you can shift your weight from your hands to your forearms. Your body should form a straight line. Brace your abs (imagine someone is about to punch you in the gut) and hold. Focus on form: Don't drop your hips or raise your butt.

Day 4. Training Tip: Move Your Butt
Your booty and your belly are unlikely partners in crime. Here's why: Over time, sitting around too much renders your glutes practically useless and causes your hip flexors—the muscles that connect your hipbones to your legs—to become stiff. This couch-potato combo tilts your pelvis forward, which increases the arch in your back and puts stress on your spine. From a cosmetic standpoint, it pushes your abdomen out, making even a relatively flat stomach bulge. That means that to lose your gut, you've got to work your butt. The glute bridge march and hip-thigh raise will help you get a stronger behind.

Combat tight hip flexors with this stretch: In a lunge position, lower yourself so your back knee is resting on the floor. Push your hips forward, keeping your back upright, until you feel a stretch in the front of your back hip. Hold for 10 seconds, relax, and repeat. Switch legs. You can increase the stretch by reaching your arms over your head.

Day 5. Slim-Down Strategy: Eat Monounsaturated Fats
Dietary fat is one nutrient with a serious image problem: "Fat in food is equated to fat on hips—but it's not the same! Our bodies need certain fats," says Bonnie Taub-Dix, R.D., author of Read It Before You Eat It. Getting the right amounts from the right sources will not only ensure your food doesn't taste like cardboard, but also can help you lose stubborn pounds (yes, you read that correctly).

A study in the journal Diabetes Care found that a diet rich in monounsaturated fats (such as almonds, avocados, and olives) may prevent the accumulation of abdominal fat. "Fat is all about the source it comes from," says Lauren Blaue, R.D., a nutrition coach at Life Time Athletic Club in Minneapolis. Combining fats and carbs in the same meal will keep your blood sugar stable and help you avoid hunger-inducing spikes and dips.

This isn't license to gorge on one ginormous cinnamon roll, though. Spread your fat-carb combos throughout the day: natural nut butter on whole-grain toast in the a.m., olive oil drizzled on your salad at lunch, guac with veggies for a snack. Learn more about good fat versus bad fat and find out how much fat you should be eating.

Day 6. Core-Sculpting Workout: 4 Amazing Abs Exercises
Jillian Michaels showed us four tough exercises—a sneak peek from her newest DVD, Jillian Michaels Killer Abs, out in September—that are meant to complement your existing workout routine twice a week. "The combination targets every muscle in your abdominal wall," she says. "If you're eating properly and doing your other training three or four times a week for 30 minutes, you'll notice a difference by the second week," promises Jillian. Get Jillian’s abs workout!

Day 7. Training Tip: Give Your Abs A Rest
You need only three sessions a week to see maximum results—really. "Training every day with endless crunches won't flatten your belly faster," says Bill Hartman, co-owner of Indianapolis Sports and Fitness. "You'll see benefits quicker if you give your muscles a day to fully recover between workouts." That's because stressing your muscles during a workout breaks down the tissues, and they need rest days to rebuild and get stronger.

What's more, you should stick to only 15 to 20 reps of each move. "If you can easily do that many, it's time for harder moves," says Rachel Cosgrove, C.S.C.S., owner of Results Fitness in Santa Clarita, California.

Still want to get your sweat on today? Try some calorie-blasting cardio with this tempo workout!

Day 8. Slim-Down Strategy: Reduce Your Stress
Anxiety can produce extra cortisol, a hormone that encourages the body to store fat, particularly in your belly. According to researchers at Yale University, your midsection is four times as likely as the rest of your body to store stress-induced fat. Another way stress sabotages your abs: When tension runs high, we reach for fattening foods.

Reduce anxiety and achieve a sense of calm in minutes with this series of relaxing yoga poses. You can also help keep stress in check by taking little breaks from work every 90 minutes. "It's almost like recalibrating your body—reminding you to breathe and relax," says celebrity trainer Valerie Waters, whose clients include Jennifer Garner.

Day 9. Core-Sculpting Workout: Standing Abs Moves
When you want to sculpt lean, sexy abs, doing crunches is highly overrated. Why? On-your-back moves target just one part of your midsection and leave out the deep-lying muscles that cinch in your waist. Our upright abdominal workout, created by Bernardo Coppola, a celebrity personal trainer in L.A., engages all the muscles you need for a bikini-worthy middle—minus the neck strain. You'll be strengthening your entire core, the dozens of muscles that make up your hips, pelvis, lower back, and abs. Bonus: You’ll also improve your posture! Get the standing abs workout—it's only four moves!

Day 10. Plank Test #2
This is the second of five plank tests. Hold a plank for as long as you can with proper form. Can you hold it longer than last week? Your goal is to build up to 90 seconds. If you can already hold a plank for 90 seconds, try these plank upgrades. You can also try a side plank—work up to holding it for 60 seconds on each side.

Day 11. Training Tip: Count to Three
It isn't easy, but when you strength train, count to three as you lower the weight (or your body weight) back to the starting position. Slowing things down increases the breakdown of muscle tissue—yeah, it sounds bad, but all that damage you're incurring is actually a good thing. The repair process pumps up your metabolism for as long as 72 hours after your session, according to researchers at Wayne State University.

But pass on those featherweight dumbbells; you need to use enough weight that you struggle to complete the final few reps. Try this challenging "burn-out sets" workout and you'll lose more when you lift more!

Day 12. Slim-Down Strategy: Plan Your Meals In Advance
If you know what’s for dinner (and you already have the ingredients), you’re much less likely to cave and order takeout. Need some planning help? Print our one-week eating plan: You'll eat well and stay satisfied with healthy 1,500-calorie menus from Keri Glassman R.D. Each delicious day includes breakfast, lunch, dinner, two snacks, and dessert.

Day 13. Core-Sculpting Workout: 360-Degree Abs Routine
Your abs aren’t only on the front! They're an intricate system of muscles, connecting to your rib cage, your hips, and even your backbone. To get a strong, sculpted core, you not only need belly exercises but also lower-back strength and exercises for your obliques (the abdominal muscles that run down the sides of your torso). TRY IT: These fat-burning abs exercises work all of the key regions of your core: upper abs, lower abs, obliques, and lower back.

Day 15. Crazy-Tough Move: The Twisting Windmill
We bet you haven't tried this oblique-targeting exercise before. To do this move, lie on your back with your arms out to the sides and raise your legs straight in the air. Lower your legs to the left side of your body, bring them back to center, then lower them to the right. That's one rep. Try to do 12 reps of the twisting windmill!

Day 16. Core-Sculpting Workout: Yoga For Great Abs
With the right yoga moves, you can makeover your ab routine to build a strong, sexy core more efficiently. Hilary Lindsay of Active Yoga in Nashville developed this core-on-the-floor sequence that hits every major abdominal muscle. "These movements are hands down more effective [than traditional crunches]," says Dr. Michele Olson, professor of exercise science at Auburn University in Montgomery, Alabama. "They activate the core muscles to a much greater degree." Try our yoga for abs routine!

Day 17. Plank Test #3
This is the third of five plank tests. Hold a plank for as long as you can with proper form. Can you hold it longer than last week? Your goal is to build up to 90 seconds. If you can already hold a plank for 90 seconds, try these plank upgrades. You can also try a side plank—work up to holding it for 60 seconds on each side.

Day 18. Sneaky Toner: Flex Time
Maybe you’ve heard of muscle memory: the way your body learns to do a physical activity (like riding a bike) and never forgets. Well, your abs have a memory, too. If you consciously keep your abs firm throughout the day, they’ll tend to stay firm even when you’re relaxed.

When you’re sitting in your car or at your desk, tense your middle as you would at the start of the crunch. Sit up straight and pull your abs in for 60 seconds at a time, at least once an hour. Anytime you feel them going slack throughout your day, tighten them up again. You're more than half-way through your 30 day ab challenge, keep it up!

Day 19. Slim-Down Strategy: Drink More Green Tea
"It's the closest thing to a metabolism potion," says Tammy Lakatos Shames, R.D., author of Fire Up Your Metabolism: 9 Proven Principles for Burning Fat and Losing Weight Forever. The brew contains a plant compound called ECGC, which promotes fat burning. In one study, people who consumed the equivalent of three to five cups a day for 12 weeks decreased their body weight by 4.6 percent. According to other studies, consuming two to four cups of green tea per day may torch an extra 50 calories. That translates into about five pounds a year. Learn more about the health benefits of green tea!

Day 20. Core-Sculpting Workout: Flat-Abs Pilates Routine
You've probably read about celebs extolling the virtues of Pilates (lean legs, a supertaut tummy!), or maybe even heard the hype from mat-class–obsessed friends. If you're still skeptical, keep reading: "Pilates puts your muscles—especially the smaller, stabilizing ones—under constant tension over a large range of motion to create that enviable long, lean look," says Lauren Piskin, owner of Physicalmind Studio in New York City.

What's more, one study found that women who swapped their usual routines for two 60-minute Pilates sessions a week saw significant increases in abdominal endurance, hamstring flexibility, and upper-body muscular endurance. Try the flat-abs pilates workout or see a video of the routine to amp up your 30 day ab challenge!

Day 21. Sneaky Core Toner: Pushups
The pushup may well be the best exercise for women. Why? Regularly adding pushups to your workout won't just strengthen your chest. It will also shape your shoulders, triceps, and glutes while toning and tightening your entire core. Working all those muscles at once torches tons of calories and can even help give your girls an extra boost. Really, could you ask anything more of a single exercise? Try these eight pushup variations!

Day 22. Core-Sculpting Exercises: Bust A (New) Move
If your core routine gets boring, you'll be less motivated to do it. Plus, trying new moves will challenge your body and help you get stronger and leaner. Have you ever done a wide-stance plank with opposite arm and leg lift? We didn't think so. How about a weighted Russian twist? Check out these three core moves!

Day 23. Slim-Down Strategy: Lean to the Left
If you have an emergency stash of Cheetos, keep them in a left-hand desk drawer. Researchers at Dartmouth College found that we're more likely to reach for things to the right of our field of vision regardless of handedness. Even better: Keep fruit on your desk in a prime right-hand spot so it will be an obvious snack choice. Need more healthy snack ideas? Try one of these 100-calorie snacks!

Day 24. Plank Test #4
This is the fourth of five plank tests. Hold a plank for as long as you can with proper form. Can you hold it longer than last week? Your goal is to build up to 90 seconds. If you can already hold a plank for 90 seconds, try these plank upgrades. You can also try a side plank—work up to holding it for 60 seconds on each side.

Day 25. Core Sculpting Workout: Get Gold-Medal Abs Like Rower Susan Francia
With the serious total-body strength that rowing demands, it's no surprise that Susan Francia, 2008 Olympic rowing gold medalist, rocks some killer abs. Her winning secret: core stability. Each of the exercises in this workout engages your entire core by challenging it to keep your body stable and your spine neutral during every rep. Try the Olympic abs workout!

Day 26. Slim-Down Strategy: Munch More Often
Doctor’s orders: Manage your body's energy needs over the course of a day so that you're never too hungry to think straight. If your food supply slacks off, even for a few hours, it's an invitation to gluttony, says Travis Stork, M.D., and author of The Lean Belly Prescription. An easy fix: Eat every three hours, beginning with breakfast.

A study from the University of Massachusetts Medical School determined that people who skip breakfast are four and a half times more likely to be obese than those who make time for it. During your 30 day ab challenge be sure that each of your snacks has a good mix of protein, fat, fiber, and carbs. Eating on this schedule will solve the biggest problem people face when it comes to losing weight: being too hungry to keep it up.

Day 27. Training Tip: Warm Up
Want to perform your best? Ease into your workout. Research shows that warm-ups increase the speed of contraction in your muscles. “The best way to warm up is with dynamic stretching," says Nick Tumminello, owner of Performance University in Baltimore, because it increases flexibility, improves blood flow, and decreases your risk of injury and your recovery time. Try this dynamic warmup before your next gym session.

Day 28. Core-Sculpting Workout: Stability Routine
Stability exercises improve your posture, strengthen your core, and help you achieve a toned head-to-toe physique, says Nick Anthony, performance specialist at Core Performance in Phoenix, who designed this routine. And since your core is constantly engaged throughout each exercise, you'll get a killer ab workout to boot! Try the stability workout.

Day 29. Crazy-Tough Move: Side Pillar Jacks
Give this killer exercise a try: Get into a side plank, then raise your top leg as high as you can and hold for 2 seconds. Lower it back to the starting position. That’s one rep. How many reps can you complete with proper form? (If the answer is zero, start by holding side planks first.) See what side pillar jacks look like.

Day 30. Slim-Down Strategy: Pow(d)er Up
Don't be fooled by labels featuring ripped, bulked-up dudes. Anyone, jock or not, can benefit from the belly-flattening power of protein powder. Opt for whey protein over soy: According to a study in The Journal of Nutrition, participants whose diets included whey protein for 23 weeks had less body fat and a smaller waist than those who consumed soy protein. In fact, as strange as it sounds, dieters who included whey protein in their eating plan doubled their fat loss compared with those who ate the same number of calories but didn't drink any shakes.

To reveal your abs once and for all, try including whey protein in yogurt or a shake once a day or at least a few times a week during your 30 day ab challenge. See even more flat-belly eating strategies.

Day 31. Plank Test #5
This is the last day of the Abs Challenge and the final plank test!

Hold a plank for as long as you can with proper form. Your goal is to build up to 90 seconds. If you can already hold a plank for 90 seconds, try these plank upgrades. You can also try a side plank—work up to holding it for 60 seconds on each side.